高速列车用Al7SiMg合金的应力腐蚀性能研究

Study on stress corrosion behavior of Al7 SiMg alloy for high speed train

对高速列车铸件用的Al7SiMg铝合金试样,分别在空气和NaCl水溶液环境中进行慢应变速率拉伸性能测试,比较其测试数据结果及断口形貌,研究Al7SiMg合金的应力腐蚀性能.研究结果表明:在质量分数为3.5%的NaCl水溶液环境中的拉伸性能略低于空气中的,在空气环境中测得的抗拉强度与NaCl水溶液环境中测得的抗拉强度之比值为0.96,而相应的两种环境中测得的伸长率之比例为0.85,计算得到的ISSRT指数为0.049.观察试样断口形貌可以看出,Al7SiMg合金试样在质量分数为3.5%的NaCl水溶液环境中与空气中拉伸均表现出韧性断裂为主、存有少量沿晶开裂的特征,Al7SiMg合金的应力腐蚀并不敏感.

The slow strain rate tension(SSRT)test was conducted on Al7 SiMg aluminum alloy samples used for high-speed train casting in air and NaCl aqueous solution respectively.The results of the test data and fracture morphology were compared to study the stress corrosion behavior of Al7SiMg alloy.The results show that the tensile properties of Al7SiMg alloy in aqueous solution with a mass fraction of 3.5%NaCl are slightly lower than those in air.The ratio of tensile strength and elongation measured in air and NaCl aqueous solution are 0.96 and 0.85 respectively,and the calculated ISSRT index is 0.049.According to the fracture morphology of the sample,ductile fracture dominates the Al7SiMg alloy sample in the corresponding two environment.Al7SiMg alloy is not sensitive to stress corrosion due to a small amount of intergranular cracking.